Arc bit point for rock drills



Sept. 12, 1944. P. 5. BROWN 2,358,052

ARC BIT POINT FOR ROCK DRILL S Filed Aug. 27, 1942 FIG. 2.

Philip El .E'nnwn /f A; 49/ ATTORNEYS.

INVENTOR.

Patented Sept. 12, 1944 ARC BIT POINT FOR ROCK DRILLS Philip B; Brown, Pan-al, Mexico Application August 27, 1942, Serial No. 456,419

Claims.

This invention relates to improvements in rock drills.

The primary object of this invention is the provision of an improved rock drill wherein the initial penetrating or cutting edges proceeds circumferentially so as to eliminate as much as possible unnecessary abrasive action upon the cutting edges; thereby insuring of a quick eco nomical drilling action with but little mainte nance cost.

A further object of this invention is the provision of an improved drill having arc-shaped cutting edges at the outer periphery of the drill and including a substantially centrally disposed penetrating cutter; said cutting edges and cutter being so arranged as to isolate a section of the rock being drilled and which is subsequently crushed by a shoulder provided upon the bit intermediate the cutting edges and the central penetrating cutter.

Other objects and advantages of this invention will be apparent during the course of the following detailed description.

In the accompanying drawing, forming a part of this specification, and wherein similar reference characters designate corresponding parts thruout the several views,

Figure 1 is a side elevation of the improved drill.

Figure 2 is a side elevation of the drill taken at an angle of 45 with respect to the view shown in Figure 1.

Figure 3 is a bottom plan view of the drill showing the cutting and crushing edges.

Figures 4 and 5 are fragmentary sectional views showing features of the improved drill.

In the drawing, wherein for the purpose of illustration is shown only a preferred embodiment of the invention, the letter A may generally designate the improved drill, which may comprise a bit integral with a drill rod; a detachable bit; or a bit head of any approved nature.

This drill A includes a body portion H! of generally cylindrical formation having the laterally extending and depending shanks ll. They are preferably four in number and arranged at angles of 90 with respect to each other. These shanks may be integral or detachable with respect to the body l0 and they depend below the normal convex surface I! of the body l0, and upon them are provided certain cutting and crushing edges to be subsequently described.

The body In is preferably provided with a centrally disposed penetrating cutter point H, which projects below the convex surface I! for the proper distance, depending upon the formation of the rock to be cut into.

The shanks ll each provide, at the outer,- periphery thereof, an arcuate cutting edge [5 wards the axis of the bit or drill, and the cutter I5 has the inner surface ll sloping inwardly divergent with respect to the surface l6.

Each shank II has a bluntly formed crushing shoulder or edge 20 located about midway between the penetrating point It and the cutting edge l5. It should be noted that the bottom of the cutter point I4 lies flush with the cutting edges IS; the latter all being in the same plane normal to the longitudinal axis of the drill or bit head A. The crushing shoulders 2|! have their convex surfaces spaced from the plane in which the cutter edges of cutter members I4 and I5 lie, so that these crushing shoulders do not act to crush the isolated section of rock between the cutter point l4 and the cutter edges l5 until after the cutters have penetrated the desired distance to permit of facile crushing of this isolated rin shaped section of rock.

If desired, the cutting feature of .the improved drill or bit may include a radially disposed cutting edge 25 between the crushing shoulder 20 and the cutting edge I 5, upon-each of the shanks II; this cutting edge 25 being located above the plane in which the convex surfaces of the crushing shoulders 20 lie, and sloping therefrom in each direction upwardly into the shank.

The mode of operationof the improved drill will be apparent from the foregoing. The cutting point M and cutter edges l5 of course initially penetrate the rock and isolate a ring-shaped section therebetween which is crushed upon impact of the shoulders 20. This permits of expeditious drilling, and with considerable economy. The maintenance of the drill is also less than with conventional drills since there is no transverse cutting action upon which abrasion has the effect of quickly dulling the cutting edges, as in conventional drills.

As beforementioned, the improved drill may include a bit head integral with a drill rod; it may be a detachable bit head, and it is within the contemplation of thisinvention to detachably mount the shanks II, as well as the cutter points, edges and crushing shoulders.

The drill may be provided with water passageways 30, which at the lower end branch outwardly in any approved relation, and open upon the bottom of the body I!) adjacent to but so as not to interfere with the cutting action of the point H.

Various changes in the shape, size and arrangement of parts may be made to the form of invention herein shown and described, without departing from the spirit of the invention or the scope of the following claims;

I claim:

1. In a drill, the combination of a body having an arcuately disposed cutting edge spaced from the axis thereof, a centrallydisposed penetrating cutter, and a crushing shoulder between the said cutter and cutting edge disposed with its lower edge in a plane above the normal penetrating and cutting surfaces of said cutter-and cutting edge.

2. In a drill, the combination of a body having a plurality of relatively spaced, laterally extending and depending shanks projecting below the lower surface of the body and having arcuate cutting edges thereon, a centrally disposed cutter upon said body spaced in predetermined relation from said cutting edges of the shank, and rock crushing shoulders between said last mentioned cutter and the said cutting edges, said rock crushing shoulders being disposed with the front crushting plane of said penetrating and cutting means,

4. A rock drill comprising a body having a depending centrally disposed penetrating and cutting point, relatively spaced arcuate cutting edges upon said body at the outer periphery thereof and struck from the axis of the body as a center, and crushing shoulders disposed in the spaces between said cutting point and arcuate cutting edges, said crushing shoulders having blunt convex surfaces disposed in a plane above the normal cutting plane oi said point and cutter edges.

5. In a rock cutting drill bit the combination of a-body having depending relatively spaced inner and outer sharp rock cutters, and depending bluntly surfaced rock crushing means upon the body in the space between said inner and outer cutters, the depending bluntly surfaced crushing means being disposed with its lowermost surface in a plane above the cutters aforesaid.

PHILIP B. BROWN. 

